Hydraulic mechanism, especially plural cylinder system and control therefor



F. T. COURT IIECHANISH,

Sept. 28, 1948.

HYDRAULIC ESPECIALLY PLUHAL CYLINDER SYSTEM AND CONTROL THEREFOR Filed lay 24, 1945 5 Sheets-Sheet 1 FI|IIIL||||||| FIG. I

INVENTOR.

ATTORNEYS Sept. 28, 1948. F. T, COURT HYDRAULIC IBOKANISH, ESPECIALLY PLURAL cnmmm SYSTEM AND cou'rnoz. mannvoa 5 ShBetsPSheet 2 Filed lay 24, 1945 llllll l I INVEN TOR.

Sept. 28, 1948. 1'. COURT 2,450,270

HYDRAULIC lBCl-IANISI, ESPECIALLY PLURAL CYLINDER SYSTBI AND CONTROL THEREFOR Filed May 24, 1945 5 Sheets-Sheet 3 INVEN TOR.

FRANK T. OOURT Sept. 28, 1948. F. T. COURT IECHMIISI, ESPECIALLY PLURAL HYDRAULIC v CYLDIDBR SYSTEI AND CONTROL THEREFOR Filed lay 24, 1945 5 Sheets-Sheet 4 FIG. 5

A JNVENTOR. FRANK T. COURT Sept. 28, 1948. COURT 2,450,270

HYDRAULIC MECHANISM, ESPECIALLY PLURAL CYLINDER SYSTEM AND CONTROL 'I'iiERI-IFOR Filed llay 24, 1945 5 Sheets-Sheet 5 IN VEN TOR. FRANK T. COURT ATTORNEYS Patented Sept. 28, 1948 HYDRAULIC MECHANISM, ESPECIALLY PLURAL CYLINDER SYSTEM AND GON- TROL THEREFOR Frank T. Court, Molina, Ill., assignor to Deere & Company, Molina, III., a corporation oi Illinois Application Ma! 24, 1945, Serial No. 595,831

17 Claims. (01. Bil-97) The present invention relates generally to hydraulic mechanism and is most advantageously applied to hydraulic power lift mechanism for raising and lowering implements associated with the tractor, either mounted on the latter or propelled thereby, and has for its principal object the provision of a novel and improved hydraulic power lift mechanism that is simple and compact, but which can be employed for a greater number of diversified operations than mechanism heretofore known in the art, and which can be quickly and easily converted from one type of control operation to another.

A further object relates to the provision of a hydraulic power lift device for tractors, including two independently controlled rockshafts for independently raising and lowering the implements mounted on opposite sides of the tractor, selectively, such as, for example, cultivating or planting implements when used on pointed rows.

Still another object relates to the provision of a power lift device including two cylinders and two rockshafts, together with dual control mechanism therefor, contain in a unitary compact housing structure which can be mounted over the rear opening in a rear axle housing of the banjo type. In the accomplishment of this object, I have provided a unitary self-contained housing structure which can be substituted for the conventional power lift housing shown and described in Patent 2,302,637 granted to McCormick and Hansen, November 17, 1942.

Still another object relates to the provision of power lift mechanism including two cylinders for actuating two separate rockshafts, the cylinders being driven by a single hydraulic pump and controlled by valve mechanism which provides for actuation of the rockshaft at a uniform speed, regardless of whether the rockshafts are actuated simultaneously or independently. Either of the cylinders can be actuated independently, and the other cylinder can be started moving before the first cylinder has reached the end of its travel, without changing the speed of movement of the latter.

Although the rockshafts and their connected cylinders are preferable for use with tractor mounted implements, it is frequently desirable to mount control cylinders on trailing implements, such as corn pickers, combines, and the like. It is desirable, however, to use as much as possible of the tractor mounted hydraulic mechanism, such as the control valve mechanism and the pump and reservoir, for controlling the remote cylinders, and therefore it is another object ill 0! my invention to provide means for quickly and easily connecting one or two remote cylinders to the integral valve control mechanism for controlling the remote cylinders from the tractor operator's station. A related object has to do with the provision of suitable 3-way valves incorporated in the unitary valve control mechanism, by means of which the built in cylinders can be cut out of the hydraulic circuit and the remote cylinders connected to the valve mechanism for actuation thereby.

Another object of my invention has to do with the provision for moving the remote cylinders at the same speed of operation, regardless of whether they are controlled independently or simultaneously.

A still further object relates to the provision of control mechanism for the integral cylinders including control levers which move through a distance proportional to the distance of travel of the associated hydraulic cylinders, whereby the position of the control lever at any time is an indication of the position of the piston in the cylinder. A related object has to with the provision of means for applying this same control principle to a remote cylinder. In this connection, it is an object to provide control connections by which a remote cylinder can be connected to one of the valve mechanisms in place of its associated tractor mounted cylinder, while the other tractor mounted cylinder is used as a metering cylinder to measure the amount of oil flowing either into or out of the remote cylinder, in order to syn chronize the movements of the operators control levers with the movements of the remote cylinder, thus causing the position of the operator's levers to serve as an indication of the position of the piston in the remote cylinder.

These and other objects and advantages of my invention will be apparent to those skilled in the art after a consideration of the following description, in which reference is had to the drawings appended hereto, in which Figure l is a side elevational view of the banjo type rear axle housing of a tractor, with power lift mechanism mounted thereon, embodying the principles of the present invention.

Figure 2 is a rear view of the axle housing and power lift mechanism, partly broken away to show details of construction, and showing a remote cylinder connected to one of the control valve units.

Figure 3 is a bottom plan view of the power lift mechanism, a portion of which is broken away to show in section certain of the cylinders and ducts.

Figure 4 is an elevational view of the control mechanism, drawn to a larger scale, showing the housing with the cylinders detached therefrom.

Figure 5 is an elevational view of the housing, drawn to a still larger scale, and showing the valve control casing in section along a plane passing through the axes of the two valve bores.

Figure 6 is a sectional view taken along a line 6-8 in Figure 5 and Figure 7 is a top plan view of the hydraulic mechanism. the top wall having a portion broken away to show the details of the rockshafts and their connections.

Referring now to the drawings, the tractor is represented by a rear axle housing ID of the banjo type, including a central gear compartment II and a pair of oppositely disposed laterally extending axle housings l2, within which are journaled the wheel supporting axles l3 in a manner well known to those skilled in the art.

A pair of drive gears M are mounted on the axles l3 and project rearwardly through an opening in the rear side oi the tractor axle housing According to the principles of the present invention, the power lift mechanism includes a main housing II, disposed in a generally vertical position over the rear opening in the banjo housing and secured to the latter by a plurality of bolts Ill, extending through suitable apertures in the housing I! and the axle housing I I. The main housin comprises a centrally disposed gear chamber l'l, into which the drive gears ll project and are enclosed thereby. A pair of vertically disposed fore and at extending walls II! are spaced inwardly from the two end walls IQ of the housing II, and each pair of walls l8, l9 defines the sides 0! a reservoir chamber Ill. The reservoirs are also provided with a front wall 2| lying against the back wall flange of the axle housing II. The rear side of each of the reservoirs II is open from the top to the bottom oi the main housing IS, the openings being indicated by reference numeral 22. The two reservoirs 20 are interconnected by a transverse passageway or duct 13. cast integrally with the bottom wall 24 of the main housing I! and extending through the central chamber H.

A pair of cylinder castings II are secured in laterally spaced, vertically disposed positions, on opposite sides of the rear side wall ll of the main housing II. The cylinder castings 3|! are provided with flanges 32, which are secured to the wall II by bolts 33, which extend through suitable apertures in the flanges 3! and through sultabie threaded openings N in the wall ii. The cylinder castings 3|! act as closures for the reser voir openings 22. The cylinder castings II are provided with cylinder bores 35, disposed on vertical axes. the lower ends 01' the bores 35 being closed by end walls 38. A piston 81 is slidable axially within each bore 35 and is provided with an upwardly extending piston rod II. The upper end 0! each cylinder bore 35 is closed by a wall II. which is suitably apertured to allow the piston rod II to extend upwardly therethrough. the aperture being sealed by a sealing gland indicated at ill in Figure 1.

The upper portion of the main housing I! contains a pair of transversely disposed rockshaits l8, l8, which are disposed in coaxial alignment with their inner ends spaced slightly apart at the center oi the housing I! and their outer ends iournaled in laterally extending sleeves 41, cast integrally with the housing IS. The outer ends of the rockshaits 45, 46 are squared, as indicated at II, for the purpose of receiving suitable lii'ting arms, to which implement iii ting connections can be made, as is well known to those skilled in the art. inwardly of the supporting sleeves 41, the rockshafts are provided with a second squared portion 50 (see Figures 4 and '7), each of which receives a hub 6|, formed integrally with an actuating arm 52. The hub ii is provided with a square internal aperture, which receives the squared portion ill of the associated rockshaft and is non-rotatable thereon. Inwardly of the squared portion 50, each or the rockshatts is provided with a cylindrical bearing portion 53 of reduced diameter, which is Journaled in a bearing sleeve 54, formed integrally with the inner vertical wall l8. A collar it fixed to the inner portion 53 of each rockshaft by a set screw 56, retains the rockshafts within the housing and prevents them trom sliding laterally outwardly therefrom.

The outer end of each of the actuating arms I2 is provided with a ball crank 51, rigidly fixed thereto, while the upper end of each of the piston rods 38 is also provided with a ball 59 secured to its upper end. The two balls 51, 59 are interconnected by a pair of link members 60 rigidly clamped together by bolts 8|. Each of the link members is provided at opposite ends thereof. respectively, with a substantially hemispherical bearing portion 82, the two portions 82 at either end of the links 80 cooperating to receive the balls 51, 59. to form ball and socket Joints for swingably connecting the links '80 with the arm 52 and piston rod Ill. Each of the arms 52 extends rearwardly through the opening 22 to position the ball 51 substantially directly above the ball 59, so that vertical movement of the piston 31 in the cylinder bore 35 transmits force through the links 60 to the arm 52, thereby rocking the associated rockshait about its major axis.

Upper housing portions 85 enclose the links 80 and their ball and socket joints and are provided with laterally extending flanges it, which lie flat against the wall 3| of the main housing It and are secured thereto by bolts 81. which extend through apertures in the flanges I6 and through suitable threaded openings 68 in the wall 3 l The adjacent edges of the housing portion 65 and cylinder casting 30 are provided with abutting flanges 80, which fit tightly together to prevent any leakage of oil therebetween. The housin portions .5 are provided with rounded top walls 10, which meet the top wall 'II of the main housing portion II and thus totally enclose the connections between the piston rods and the actuating arms 52.

Hydraulic fluid. such as oil, is provided under pressure for actuating the pistons 31 in the bores 36 by means of a pump, indicated in its entirety by reference numeral ll, comprising a flanged cover or housing ll secured to the main housin wall II by bolts 82. A pair of intermeshing pump gears I3. 84 (Figure 4) is disposed within the pump housing II, and operates in a well known manner to propel the hydraulic fluid from a low pressure port II to a high pressure discharge port II. The pump gear 84 is mounted on a tractor power takeofl shaft 81 which extends rearwardly through the lower portions of the axle housing II and the main power lift housing II, and is Journaled in a bearing 88 in the pump housing II.

The low pressure port It is connected by a short passageway or duct 89 with the intercon- I necting duct 22 (Figure 4). and is preferably formed integrally with the housing wall 0 I.

The high pressure port 00 connects with a supply duct 00 which extends upwardly therefrom. The port 00 is also connected with a short relief duct II (see Figure 4), which is normally closed by a poppet valve 02, the latter being urged into closed position by a strong compression spring as which reacts against a plug 00 in the bottom wall 20 of the housing I0. The duct DI also connects with the transverse connecting duct 22 and the spring 00 is yieldable to pressures appreciably higher than normal operating pressures to prevent damage to the power lift mechanism in case of overload.

The power lift cylinders are controlled by valve mechanism contained in a valve casing I00 disposed directly above the pump housing II between the two cylinders and secured to the housing wall II by bolts "I. As will be made clear in later detailed description, the fluid passages in the valve housing I00 are provided with ports which register with ports in the wall 8| oi the main housing l0, and connect with the pump and the cylinders through ducts formed integrally with the wall 2| on the inner side thereof.

One of these ducts is the high pressure supply duct 80, which extends upwardly along the housing wall II from the pump discharge port 00 and terminates in a pair of vertically spaced ports I02 which extend laterally from the duct 00, as best shown in Figures 4 and 5. The ports I02 register with a pair of upper and lower intake ports I02 in the housing I00, which communicate with a valve bore I00, extending vertically from top to bottom oi the housing I00. A cylindrical piston type valve member I00 is slidable axially within the bore I00 and is reduced in diameter near opposite ends thereof, as indicated at Ill, providing three axially spaced piston portions, which close the valve bore I00 against ilow oi oi] axially therethrough, including a centrally disposed piston portion I00 and a pair of end closure portions I00.

The center portion I00 is of such length that when the valve member I00 is disposed in its central neutral position, as indicated in Figure 5. the oil is discharged through the intake ports III into the valve bore I00 at opposite ends oi the central portion I00. A pair of discharge ports III is provided in the valve bore I00 at opposite ends of the valve member I00, respectively, and the reduced diameter portions I01 0! the valve member have a length suillcient to permit oil to flow along the portions of reduced diameter from the intake ports I02 to the discharge ports IIO, when the valve member I00 is in its neutral position. The exhaust or discharge ports 0 are interconnected by a duct III extending through the valve casing I00 parallel to the valve bore I00 and serves to conduct the fluid away from the valve bore I00, eventually returning it to the reservoir 20.

Near each end 01 the valve member ill between the intake and discharge ports Ill, III, are two ports I II, which are connected by vertically extending U-shaped ducts III with a pair oi outwardly spaced ports I" in the valve bore I00. A bushing I I0 blocks the valve bore I00 between each pair of ports III, III, and is apertured to received the valve stem III of a check valve I20. The check valve I20 is a poppet type valve, which seats in an annular closure member |2I through which the valve stem |I0 extends. The valve I20 is urged toward seated position in the annular seat I, by means of a compression spring I22, disposed within a check valve chamber lllwithinthebore l00ontheoutersideot the annular seat member I2l. Within the check valve chamber I22 is disposed a cylindrical cup shaped valve I20, the open end 01 which bears against the annular seat member I2I around the check valve I 20. and the valve member I20 i'lts closely within the bore I00. the latter being slightly enlarged around the seat member "I and outwardly therefrom. A discharge aperture I20 is provided in the cylindrical valve member I20, and the latter is rotatable within the valve chamber I23 to direct the fluid which flows through the check valve seat I2I in either of two directlons. selectively, as best shown in Figure 0.

Each of the valve chambers I20 communicates with a port l2lin the inner side of the valve casing I00. which is adapted to register with a port I2I in the wall II. The port Ill is connected in communication with a duct I22, formed integrally with the housing wall II on the inner side thereof, which inclines downwardly and outwardly to one end oi the adjacent cylinder 00. Thus, the upper valve chamber III is connected by the duct I02 to a port I in the wall II, which Is adapted to register with a port I20 in the cylinder casting 20 communicating with the cylinder bore II at the upper end of the latter. Similarly, the lower valve chamber I20 is connected by the duct I02 to a port I03 in the wall 2|, which registers with a port I00 in the lower end oi the cylinder bore 0'.

The outer side oi the valve casing III is provided with an internally threaded opening I00 at each oi the valve chambers I22 and communicating with the latter opposite the port I30. when the valve mechanism is used to control the integral cylinders 30, these openings areclosed by means of plugs "I (Figure 2) and the cup shaped valve I20 is turned with the aperture I20 registering with the port III to direct the oil from the valve chamber I20 into the duct I32.

At other times, it is desirable to use the valve mechanism for controlling remotely disposed cylinders mounted on trailing implements drawn by the tractor, and for this purpose the plugs III are removed from the openings I00 and are replaced by fittings I00, to which are connected flexible hoses I00 (see Figures 2 and 8). The hoses I00 are connected at their opposite ends to the two ends oi a remote cylinder I02, respectively, within which is disposed a piston I00 connected to a piston rod I01 which extends outwardly through a sealing gland I00 and is prov'ided at its outer end with an eye I 00 or other means for connecting the piston rod I01 to a suitable operating element on a drawn implement. When a remote cylinder is connected for operation, the cup shaped valves I20 are rotated degrees to move the discharge aperture I20 into register with the opening I00 to direct the oil into the hose I00 and at the same time to close oi! the ipiort I00, rendering the integral cylinder inopera- Each of the selector valves I20 is provided with a stem I00, which extends axially outwardly from the valve bore I00 in the valve case Ill and the valve I20 is retained in the end of the bore I00 by means 01' a bushing I00, which is screwed into the outer end of the bore I00. The bushing III is provided with an internal threaded recess Ill, through which the stem I00 extends. and is sealed by means 0! suitable packing I02 compressed within the recess around the stem ill by means otasmallerbushing Ill. Theouterendoithe 7 stem I40 is made square to receive a conventional wrench, by which the stem I40 and hence the valve I24 can be rotated to select either the port I30 or the opening I40 for discharging the oil from the valve chamber I23.

The valve mechanism described hereinabove is similar in most respects to the valve mechanism disclosed in my co-pending application, Serial No. 561,433, filed November 1, 1944, to which reference may be had, if necessary.

The operation of this valve is as follows:

With the valve member I in a central neutral position, the fluid in the pump divides through the two ports I02 and flows outwardly along the portions I0I of reduced diameter through the exhaust ports IIO into the duct III, from which it is returned to the reservoir 20 in a manner to be described later. By shifting the valve member I00 vertically within the bore I04, the piston portion I08 covers one or the other of the inlet ports I03. causing all of the oil to flow through the other of the inlet ports. For example, when the valve member I00 is shifted upwardly, the piston portion I00 completely blocks the upper inlet port I03, whereby the oil flows through the lower inlet port I03 along the lower portion I01 of reduced diameter. At the same time, the lower piston portion I00 blocks the lower discharge port I I0, preventing escape of oil therefrom, whereupon the oil flows through the port I I5 down through the U-shaped duct I I0 and back into the bore beneath the closure member H0. The pressure of the oil against the poppet valve I20 forces the latter open against the pressure of the spring I22, the oil flowing into the valve chamber I23 inside the cup shaped valve I24, and if the latter is turned with the discharge aperture I25 in register with the port I30, the oil flows through the latter and the duct I32 and port I33 into the lower end of the integral cylinder bore 35 through the cylinder port I34. Thus, the pressure is built up under the piston 31, forcing the latter upwardly and rocking the rockshaft 40 through the actuating arm 02. Upward movement of the piston 31 forces oil out of the upper portion of the cylinder bore 30 through the registering ports I34, I33, returning the oil through the inclined duct I32 to the upper check valve chamber I23 through the registering ports I3I, I30 and the aperture I20 in the selector valve I24. The upper check valve stem H0 is engaged by the valve member I00 when the latter is shifted upwardly in the bore I04, raising the valve I20 from its seat I2I and allowing the returning oil to flow downwardly through the seat member I2I, port Ill, duct IIO, into the bore I04 through the port H0. The upper exhaust port H0 is now open, permitting the oil to flow past the upper reduced portion I01 into the discharge duct III. The upward movement oi the piston 31 in the cylinder bore 35 can be checked at any point within its range of movement by merely returning the valve member I00 to neutral position, which permits the upper check valve I20 to close, thereby lockin the oil in the upper portion of the cylinder 30, and releasing the oil pressure by opening the lower exhaust port III, whereupon the lower check valve is closed by its spring I22.

The piston 31 can be lowered in the cylinder 35 by shifting the valve member I00 downwardly within the bore I04, thereby directing oil upwardly through the upper check valve I20 and through the duct I32 to the upper end of the cylinder bore 35. Simultaneously, the valve member I00 engages the stem H0 or the lower check valve I20, opening the latter, to permit oil to flow from the lower end of the cylinder bore 30 through the lower exhaust port "0 into the discharge duct III. Thus, the piston 31 on the left side of the power lift mechanism is controlled by the valve mechanism on the left side of the valve housin I00, and if desired, the integral or built in cylinder 30 can be made inoperative and the remote cylinder I42 can be substituted therefor.

The valve casing I00 also contains a second valve mechanism in the right side of the housing, for controlling the integral cylinder 30 and its piston 31 on the right hand side of the power lift housing. The second valve mechanism also comprises a vertically disposed bore I04 and valve member I00 slidable axially therein in either direction, selectively, and since the two valve mechanisms are similar in construction in all but a few details, those parts which are similar to parts already described are indicated by similar reference numerals.

One essential difference between the two valve mechanisms is that the inlet ports I03 of the right hand mechanism are connected in communication with the discharge duct III by means of short interconnecting passages I00 in the valve casing I00. Another essential difference is that the exhaust ports IIO discharge the oil into exhaust ports IBI which register with ports I02 in the wall 3I of the main housing I0. The ports I02 communicate with laterally extending passages or ducts I03, cast integrally with the housin wall 3| and communicate with the reservoir 20 on the right hand side of the housing I0.

With both valve members I00 in neutral position, the oil circulates from the pump through the supply ducts 00, inlet ports I03 of the left hand valve mechanism, passing out through the exhaust ports IIO into the discharge duct III, then through the interconnecting passages I00 into the inlet ports I03 oi the right hand valve mechanism, and through the exhaust ports III through the discharge ducts I03 to the reservoir. If the left hand cylinder 30 is controlled independently, while the right hand valve member I00 is left in neutral position, the oil discharged from the left hand cylinder bore 30 is passed through the valve mechanism in series, and through the reservoir ducts I03. The right hand cylinder can also be controlled independently by leaving the left hand valve mechanism in neutral position, whereupon the oil flows through the latter and through the duct II I to the right hand valve mechanism, which can be controlled to shift the right hand piston 31 upwardly or downwardly in the cylinder bore 30 in the same manner as described for the left hand piston.

Both pistons 31 can be shifted simultaneously in either direction, that is to say, in either the same or in different directions, by shifting the two valve members I00 from their neutral positions either upwardly or downwardly, simultaneously or successively, as desired. In any event. the oil that is discharged from one side of the left hand cylinder passes through the duct II I and is directed by the right hand valve mechanism into either end of the right hand cylinders 30, while the oil discharged from the opposite end of the latter is returned through the passages I03 to the reservoir. In the case where both cylinders 30 are loaded simultaneously, the oil must be supplied to the left hand cylinder by the pump 00 at a pressure equal to the sum of the two pressures required to move the two loads, and the pressure used in the left hand cylinder for actuating the rockshai't is the dlii'erence between the two pressures on opposite. sides oi the leit hand piston 81. In this case. of course the pressure in the low preuure end 01' the left hand cylinder II is substantially equal to the pressure in the high pregsure end of the right hand cylinder 00.

However, in this so-called series connection of the two cylinders II and the two valve mechanisms, the amount of oil received by each or the cylinders in any given time interval, is constant regardless oi whether the cylinders are controlled simultaneously or separately and therefore the rate of movement of the two rockshaits 40 is constant whether they are actuated simultaneously or separately.

The remote cylinder I42 can be connected to the valve mechanism in either the right hand or left hand position in substitution for the integral cylinder associated therewith, or two remote cylinders can be controlled by the valve mechanism in substitution for both or the integral cylinders 00. Obviously, however, it is desirable that any two cylinders which are to be operated in series connection in the manner described, be of the same volume displacement of oil in order that both cylinders can be operated through their entire length of stroke. In other words, when one remote cylinder and one integral cylinder are used in combination, it is desirable that the amount of oil required for moving the piston throughout its range of stroke within the cylinder be the same for the two cylinders, although the cylinder diameters or length of stroke need not be the same. However, when two remote cylinders are used in combination, they need not be of the same volume displacement as the integral cylinders, although it is desirable that the two remote cylinders have the same volume.

Each of the valve members I is shifted axially within its valve bore I04 by means of a gear segment I00 disposed in mesh with a rack I00 formed on the side 01' the gear member I00 in the central piston portion'lll. The gear segment I0! is formed on the end of a shalt I01, which extends through aligned openings in the valve casing I00 and the housing wall 0i and is Journalled in a bearing sleeve I00, preferably formed integrally with the housing wall 01. The inner ends of the valve actuating shafts I01 are disposed within the gear housing chamber I1 of the main housing I! and are provided with crank arms I10, which extend inwardly toward each other and carry on their inner ends a pair 01' ball shaped cranks l1l. Each of the cranks "I is swingably connected to the lower end of a vertically disposed link I12 which extends upwardly therefrom and is swlngably connected I by a suitable pivot I13 to the intermediate portion of a bell crank I14 in the upper part of the main housing ii. The links I12 extend through openings I15 in a horizontal housing partition I18 which separates the rockshaft 40 from the lower portion of the central chamber I1. The bell crank I14 has a short arm I19 connected by a pivot I80 to a short arm III, formed integrally with a hub I02 fixed to the associated rockshaft 45, the inner end of which is formed in a square cross section in order to prevent relative rotation between the hub I02 and the rockshai't. The bell crank I14 also has a relatively long upwardly extending arm I01, which is swingably connected by a suitable pivot I04 to a control rod III which extends forwardly and is connected at its forward end by a pivot 10 I00 to a control lever I01 that is pivoted at I00 on a bracket ll! rigidly mounted on the operator's plati'orm I00 01' the tractor. The two control levers I01 are disposed in side by side.

relation and are provided with suitable securing latches Ill, which engage any of a plurality oi notches I in the upper edges of the brackets III, for holding the control levers I01 in adjusted position.

By virtue oi the connections between each of the control levers I01 and its valve actuating shaft I01, the extent of movement of the control lever I01 about its pivot support III is proportional to the extent or movement oi the associated piston 01 in the cylinder bore 30, and the position 01' the control lever I01 is indicative oi. the position or the piston in the cylinder.

For example, referring to Figure l, the control lever I01 is latched at the center of its range of movement along the notched sector I", indicating that the piston 01 is substantially midway in its range of movement in the cylinder 3!. Assuming that it is desired to adiust the piston 01 upwardly in the cylinder 00, the latch Iii is disengaged by raising it through the actuating link I and the lever I I1 is swung toward the right a desired distance, and relatched by releasing the control rod I00. Inasmuch as the piston 01 is hydraulically locked within the cylinder 00 in any stationary position, the rockshaft 40 is also looked in position, and therefore movement of the lever I01 to the right swings the bell crank I14 in a clockwise direction about the pivot I00, which is held stationary bythe arm I II on the rockshait. This causes the link I12 to be shifted upwardly, thereby swinging the arm I10 upwardly and rotating the shaft I01 about its major axis in a counterclockwise direction, as viewed in Figure 5. This movement has the efl'ect oi raising the valve member I08 in the valve bore I04, directing a how of oil into the bottom of the cylinder bore 00 as explained above. Since a very slight movement oi the valve member I06 initiates a flow 01' oil into the bottom of the cylinder 00, the piston 01 immediately begins to move upwardly, acting through the arm 52 to rock the rockshaft 40 in a counterclockwise direction, as viewed in Figure 1, thereby swinging the arm III downwardly and thereby shifting the link I12 and arm I10 downwardly to return the valve member I06 to the neutral position. Hence, a short movement of the lever I01 toward the right, as viewed in Figure 1, will adjust the piston 31 a short distance upwardly in the cylinder 00, but if the lever I01 is continued to be moved toward the right as the rockshaft swings in a counterclockwise direction, the link pivot I10 can be raised as last as the arm pivot I is lowered by movement of the rockshaft. Thus, the arm I10 can be held in raised position, thereby maintaining the valve member I00 in raised position in the valve bore I04 and causing the piston 01 to continue it upward movement in the cylinder 00. However, whenever the control lever I81 is latched in any adjusted position, movement of the rockshatt 45 acts through the link I12 to return the valve member I 00 to neutral position, stopping the movement of the piston 31 in the cylinder 05.

Conversely, by moving the control lever I01 toward the left, as viewed in Figure 1, causes the bell crank I14 to be pivoted about its pivot I 00 in a counterclockwise direction, thereby moving the link I12 downwardly to rock the control shaft I61 in a clockwise direction, as viewed in Figure 5, shifting the valve member I downwardly in the valve bore I. with the result that the oil is forced into the upper end of the cylinder bore 35, urging the piston 31 downwardly therein. As long as the control lever Ifll is shifted toward the left about its pivot I88, the piston 81 will continue its movementpownwardly in the cylinder 35, but will be arrested in its movement whenever the control lever Ill is latched to one of the notches I92.

Obviously, since the follow-up action is obtained by the rotation of the rock shaft 45, this effect is not normally obtained when the integral cylinder is replaced by a remote cylinder, for when the selector valves I24 are rotated to direct oil to the remote cylinder and block any flow of oil to or from the integral cylinder. the piston 31 is hydraulically locked against movement in either direction in the cylinder bore 35, thereby rigidly locking the rockshaft associated therewith. This holds the pivot llIl stationary, but permits the bell crank I" to swing angularly about the axis of the pivot Iflll to raise and lower the link In and thus actuates the valve member IllB up or down within the valve bore I. In this case, the control lever II! has a very limited range of movement on each side of its neutral position and must be returned manually to return the valve member III! to its neutral position to stop the movement of the piston I" in the remote cylinder 2.

According to the principles of the present invention, however, I am able to quickly and easily convert the hydraulic mechanism described hereinbefore to provide a follow-up control piston for a single remote cylinder. To obtain this type of control, the remote cylinder I42 is connected as illustrated in the drawings to the left hand valve mechanism, and the two rockshafts ll, 48 are coupled together by means of a sleeve coupling IIIII (see Fig. '1). The sleeve coupling 200 is normally in the disconnected position shown in solid lines, but for the purpose now being described, the coupling is shifted laterally to the position indicated in dotted lines, connecting the rockshafts l5, l6 rigidly together. Set screws 2 are provided in the sleeve III) for securing the latter in either position. This connection can be made simply by removing a sheet metal cover 202, which closes the top of the rockshai't compartment in the center of the housing IS. The only other necessary acts of conversion are to remove a pair of valve plugs :03, 204 from their seats in a pair of ports 205, 206 in the cylinder ducts I32, I32, respectively (Figures 3 and 4). The valve plugs 20!, 2M extend transversely across the reservoir 20 and are provided with threaded head portions 201, which are engaged in threaded openings 208 in the side wall I! of the main housing I5. At these points, the wall I9 is sufficiently thick to permit a plug 2III to be threaded into the outer end of the opening 208 to prevent the valves 203, 204 from being accidentally or inadvertently loosened from their seat. The remote cylinder II! is now connected in place of the left hand integral cylinder, but the follow-up valve mechanism on the latter is connected through the coupled rockshaft 45, ll to be actuated by the integral cylinder on the right side of the mechanism. Therefore, in view of the fact that the remote cylinder is in series connection with the right hand integral cylinder, and the two cylinders are preferably of the same fluid capacity,

12 they will reach the end of their stroke at the same instant, and therefore if they are controlled together the integral cylinder will serve as a metering cylinder for the remote cylinder, and hence the follow-up mechanism will cause the control levers III to serve as an indication of the position of the remote piston M6 in the cylinder I42. Hence, it is but necessary to move the two control levers I81 together, thereby moving the piston in the remote cylinder and the piston in the right hand integral cylinder in unison, and since the rockshafts are coupled together the left hand piston 31 is raised and lowered in its cylinder while the fluid in that cylinder is caused to flow in and out through the open ports 205, 208 with substantially no pressure being developed.

The control levers I" can be moved together by the operator and for this purpose can be placed close enough together to make it possible for him to operate both levers with one hand; alternatively this result can be facilitated by interconnecting the two levers by means of a coupler 2I5 (see Figure '1) which is similar to the coupler 200 for the two rockshafts but is used to couple the two pivot pins I86, which are extended inwardly toward each other for this purpose. In Figure 7, the coupler 2I5 is shown in its disconnected position, but it may be easily connected by sliding the sleeve 2|! over the end of the right hand pivot pin I86 and securing the coupling to the two pins I88 by means of set screws 2I6. One of the latches I9I should be secured out of engagement with its sector Ill and the other control lever is then used to control the load connected to the remote cylinder.

I do not intend my invention to be limited to the exact details shown and described herein except as set forth in the claims which follow.

I claim:

1. Power lift mechanism comprising, in combination, a housing serving as a reservoir, a pair of rockshafts journaled in said housing and projecting laterally from oposite ends thereof, respeetively, one wall of said housing having a plurality of spaced openings therein, a pair of actuating means fixed to said rockshafts, respectively, and including arms extending radially therefrom through certain of said openings, hydraulic cylinders mounted at said wall of the housing and having piston rods connected with said actuating arms, respectively, and hydraulic control mechanism disposed adjacent said cylinders and mounted on wall of the housing over certain other of said openings, for controlling said cylinders.

2. Tractor power lift mechanism comprising in combination, a main housing adapted to be mounted vertically on the rear axle housing of a tractor, a pair of coaxial rockshafts journaled in the upper portion of said housing and projecting laterally from opposite ends thereof, respectively, said housing serving as a reservoir for hydraulic fluid and having a plurality of laterally spaced openings in the rear wall thereof. a pair of actuating arms fixed to said rockshafts in laterally spaced arrangement and extending rearwardly therefrom through two of said openings. hydraulic cylinders mounted on said rear wall in vertical positions and having piston rods connected with said actuating arms, respectively, housing portions enclosing said actuating arms and piston rod connections, and hydraulic control mechanism including casing means mounted on said rear wall between said pair of cylinders over cer- 13 tain other oi said openings, i'or controlling said cylinders.

3. Tractor power lift mechanism comprising in combination, a main housing adapted to be mounted vertically on the rear axle housing of a tractor, a pair of coaxial rockshafts Journaled in the upper portion of said housing and projecting laterally from opposite ends thereof, respectively, said housing serving as a reservoir for hydraulic fluid and having a plurality oi laterally spaced openings in the rear wall thereof, a pair of actuating arms flxed to said rockshafts in laterally spaced arrangement and extending rearwardly therefrom through two of said openings, hydraulic cylinders mounted on said rear wall in vertical positions and having piston rods connected with said actuating arms, respectively, housing portions enclosing said actuating arms and piston rod connections, hydraulic control mechanism including a valve casing and a fluid pump casing mounted on said rear wall between said cylinders over certain other of said openings, and ducts tor hydraulic fluid, formed integrally with said main housing, interconnecting said pump and valve casings and connecting said valve casing with said cylinders, said ducts terminating in ports in said rear wall adapted to register with ports in said cylinders and casings, respectively,

4. Power lii't mechanism comprising, in combination, a housing serving as a reservoir, a pair of rockshafts Journaled in said housing and pro- Jecting laterally from opposite ends thereof, respectively, one wall of said housing having a plurality of spaced openings therein, a pair of actuating means fixed to said rockshafts, respectively, and including arms extending radially therefrom through certain of said openings, hydraulic cylinders mounted at said wall of the housing and having piston rods connected with said actuating arms, respectively, hydraulic control mechanism including a fluid pump and a valve casing mounted on said side wall between said cylinders over certain other of said openings, a pair of interconnected control valves disposed in said valve casing, said ,wall having ducts formed integrally with said housing and connecting one oi said valves with both ends of one of said cylinders and the other of said valves with the other of said cylinders, and duct means connecting said pump with one of said valves, the last named valve being adapted to direct fluid from said pump to either end of its associated cylinder, selectively, and to direct fluid from the other end of said associated cylinder to the other oi said valves, said other valve being adapted to direct the fluid to said reservoir directly, or to either end of its associated cylinder, selectively, and to direct fluid from the other end of the latter to said reservoir.

5. Tractor power lift mechanism comprising in combination, a main housing adapted to be mounted vertically on the rear axle housing of a tractor, a pair of coaxial rockshai'ts journaled in the upper portion of said housing and proiccting laterally from opposite ends thereof, respectively, said housing serving as a reservoir for hydraulic fluid and having a plurality of laterally spaced openings in the rear wall thereof, a pair of actuating arms fixed to said rockshafts in laterally spaced arrangement and extending rearwardly therefrom through two of said openings, hydraulic cylinders mounted on said rear wall in vertical positions and having piston rods connected with said actuating arms,

a,sso,avo

14 respectively, housing portions enclosing said actuating arms and piston rod connections, hydraulic control mechanism including a fluid pump and a valve casing mounted on said rear wall between said cylinders over certain other of said openings, a pair of interconnected control valves disposed in said valve casing, said wall having ducts formed integrally with said main housing connecting one a: said valves with both ends of one of said cylinders and the other of said valves with the other of said cylinders, and duct means connecting said pump with one of said valves. the last named valve being adapted to direct fluid from said pump to either end of its associated cylinder, selectively, and to direct fluid from the other end of said associated cylinder to the other of said valves, said other valve being adapted to direct the fluid to said reservoir directly, or to either end of its associated cylinder, selectively, and to direct fluid from the other end of the latter to said reservoir.

6. Power lift mechanism comprising, in combination, a housing serving as a reservoir, a pair of rockshafts journaled in said housing and pro- Jecting therefrom, one wail of said housing having a plurality of spaced openings therein, a pair of actuating means flxed to said rockshafts, respectively, and including arms extending radially therefrom through certain of said openings, hydraulic cylinders mounted at said wall of the housing and having piston rods connected with said actuating arms, respectively, hydraulic control mechanism disposed alongside said cylinders and mounted at said wall of the housing over certain other of said openings, for controlling said cylinders, said control mechanism including means for connecting the same to re-- motely disposed cylinders, and a plurality of 3- way valve's associated with said control mechanism for connecting the latter either to said mounted cylinders or to said remote cylinders, selectively.

7. Tractor power lift mechanism comprising in combination, a main housing'adapted to be mounted vertically on the rear axle housing of a tractor, a pair of coaxial rockshafts journaled in the upper portion of said housing and proiecting laterally from opposite ends thereof, respectively, said housing serving as a. reservoir for hydraulic fluid and having a plurality of laterally spaced openings in the rear wall thereof, a pair of actuating arms flxed to said rockshaits in laterally spaced arrangement and extending rearwardly therefrom through two of said openings, hydraulic cylinders mounted on said rear wall in vertical positions and having piston rods connected with said actuating arms, respectively, housing portions enclosing said actuating arms and piston rod connections, hydraulic control mechanism including a valve casing and a fluid pump casing mounted on said rear wall between said cylinders over certain other of said openings, and ducts for hydraulic fluid, formed integrally with said main housing, inte'rconnecting said pump and valve casings and connecting said valve casing with said cylinders, said ducts terminating in ports in said rear wall adapted to register with ports in said cylinders and casings, respectively, said control means including means for connecting the same to remotely disposed cylinders, and a plurality of 3- way valves associated with said control valves for connecting the latter either to said cylinder ducts or to said remote cylinder connections, selectively.

8. Power liit mechanism comprising a casing having a cylindrical bore provided with inlet and outlet ports, there being chambers provided in either end oi said casing, respectively, a piston type valve member shiitable axially within said bore to direct hydraulic fluid between said ports, selectively, poppet type check valves disposed adjacent opposite ends of said bore, respectively, and having stems engageable by said valve membet for connecting said valve bore in communication with said chambers, respectively, each of said chambers having a pair of ducts connected therewith, and a 3-way valve disposed in each of said chambers and shiftable to connect either of said ducts in communication with the associated chamber and to close the other of said ducts, selectively, and a pair of hydraulic motors connected with said pair of ducts, respectively.

9. Power lift mechanism comprising a casing having a cylindrical bore provided with inlet and outlet ports, a piston type valve member shiftable axially within said bore to direct hydraulic fluid between said ports, selectively, closures dispwed in said bore beyond opp site ends of said valve member defining a pair or check velve chambers, said closures being apertured to provide check valve ports, a poppet type check valve disposed in each of said check valve ports and having inwardly directed valve stems adapted to be engaged by said piston valve member, each of said chambers having a pair of ducts connected therewith, a pair of double acting cylinders, one end oi each cylinder being connected to said pair of ducts, respectively, leading to one of said chambers, and the other end of each cylinder being connected, respectively, to the pair of ducts leading to the other of said chambers, and a 3- way valve associated with each chamber for connecting the latter with either of said ducts connected thereto, selectively.

10. The combination set forth in claim 9, including the further provision that each of said 3-way valves comprises a cup-shaped element disposed ln said chamber enclosing the check valve and rotatable about the axis oi said bore, said element having a port rotatable into register with either of said ducts, selectively.

11. The combination set forth in claim 9, including the further provision that each of said 3-way valves comprises a cylindrical element journaled in the outer end of said bore inside the check valve chamber and having an open end enclosing said check valve and bearing against said closure member to receive fluid from said check valve, the outer end or said element having a stem extending out of said bore, a closure bushing in the outer end of said bore and apertured to receive said stem, said chamber having ports in the cylindrical wall thereof to which said ducts are connected, and said element having a port rotatable into register with either of said wall ports by turning said stem from outside said chamber to connect the latter with either or said double acting cylinders, selectively.

1 Tractor power lift mechanism comprising, in combination, a main vertically disposed housing serving as a reservoir, a pair of coaxially aligned rockshafts journaled in the upper portion of said housing and projecting laterally from opposite ends thereof, respectively, one side wall of said housing having a plurality of laterally spaced openings therein, a pair of actuating arms fixed to said roclrshafts, respectively, and extending radially therefrom through certain of said openings, hydraulic cylinders mounted on said side of the housing in vertical positions and having piston rods connected with said actuating arms, respectively, hydraulic control mechanism including a fluid pump and a valve casing mounted on said rear wall between said cylinders over certain other of said openings, said valve casing having a pair 01' cylindrical bores provided with inlet and outlet ports, a piston type valve member shiftable axially within each of said bores to direct hydraulic fluid between said ports, selectively, said wall having ducts formed integrally with said main housing connecting the inlet port of one of said bores with said pump, duct means connecting an outlet port of said one bore with an inlet port of the other of said bores, an outlet port of the latter being connected with said reservoir, closures disposed in each of said bores beyond opposite ends of said valve member deflning a pair of check valve chambers therein, said closures being apertured to provide check valve ports, a poppet type check valve disposed in each of said check valve ports and having inwardly directed valve stems adapted to be engaged by said piston valve member, each of said chambers having a port connected by duct means in said housing with one end of one of said mounted cylinders, the two chambers associated with opposite ends of each bore being connected with the two ends of one of said cylinders and the two chambers associated with the other bore being connected with the two ends of the other cylinder, respectively, a pair of hose connections associated with each of said valve bores for connecting opposite ends of a remotely disposed double acting cylinder with said check valve chambers, respectively, and 3-way valve means disposed in each oi said chambers for connecting each or said bores either to the said mounted cylinder or the said remote cylinder associated therewith, selectively, said valve member in said pump connected bore being shiftable in opposite directions to direct fluid from said pump to either of said valve chambers for distribution to one end of either of the double acting cylinders associated therewith, and to direct fluid from the other end of the last mentioned cylinder to the other of said valve bores, the piston valve member in the latter being shiitabie from a neutral position in which the fluid is directed to the reservoir directly, to opposite active positions for directing the fluid to either end of the selected double acting cylinder associated therewith, the fluid from the other end of the latter being discharged to the reservoir.

13. In hydraulic mechanism comprising a pair of double acting hydraulic power cylinders, pistons double acting hydraulic power cylinders, pistons shii'table therein, a control valve for each cylinder, duct means connecting each of said valves with both ends of its respective cylinder, each valve having a member shiitable in opposite directions {tom a neutral position for directing hydraulic fluid into either end of the cylinder, selectively, a power driven pump connected to deliver fluid to one of said valves for delivery into either end of the associated cylinder, connections between said valves to direct fluid from the other end of the last mentioned cylinder to the other of said valves for delivery into either end of the other of said cylinders, a discharge port in said other valve for discharging fluid from the opposite end of said other cylinder, a control lever for each valve and a diilerential connection between said associated control lever, valve member, and

piston whereby said valve member is shifted by said control lever to initiate a movement of said piston in either direction, said piston movement bein transmitted through said diiferentlal connection to return said valve member to neutral position to stop said piston, the combination oi a third power cylinder disposed remotely from said pair of cylinders and means for converting said hydraulic mechanism for controlling said third cylinder comprising means for connecting the latter with one of said control valves in place of the cylinder associated therewith, means for rendering said associated cylinder inoperative to prevent the latter from being subjected to pressure during operation, and means for establishing a mechanical connection between said valve members, to effect a simultaneous returning of said members to said neutral position responsive to movement of the operative cylinder of said pair of cylinders, whereby the latter cylinder of said pair serves as a metering cylinder to determine the position of said remote cylinder,

14. In hydraulic mechanism comprising a pair of double acting hydraulic power cylinders, pistons shiftable therein, a control valve for each cylinder, duct means connecting each of said valves with both ends of its respective cylinder, each valve having a member shii'table in opposite directions from a neutral position for directing hydraulic fluid into either end of the cylinder, selectively, a power driven pump connected,

to deliver fluid to one of said valves for delivery into either end of the associated cylinder, connections between said valves to direct fluid from the other end of the last mentioned cylinder to the other of said valves for delivery into either end of the other of said cylinders. a discharge port in said other valve for discharging fluid from the opposite end of said other cylinder, a control lever for each valve and a differential connection between said associated control lever, valve memher, and piston whereby said valve member is shifted by said control lever to initiate a movement 01' said piston in either direction, said piston movement being transmitted through said difi'erential connection to return said valve member to neutral position to stop said piston, the combination of a third power cylinder disposed remotely from said pair of cylinders and means for converting said hydraulic mechanism for controlling said third cylinder comprising means for connecting the latter to the one of said control valves in place of the cylinder associated therewith, means for coupling together said pistons of said pair of cylinders to move together as a. unit, and means for venting both ends of the replaced cylinder to release fluid pressure therein, whereby an adjustment of both of said control levers together effects movement of each of said pistons, the valve members being simultaneously retiu'ned to neutral by movement of the other of said pair of pistons, thereby determining the adjusted position of the piston in said remote cylinder.

15. In hydraulic mechanism comprising a pair of rockshafts, a pair of double ac ing hydraulic power cylinders having pistons connected to rock said rockshafts, a control valve for each cylinder, duct means connecting each of said valves with both ends of its respective cylinder, each valve having a member shiftable in opposite directions from a neutral position for directing hydraulic fluid into either end of the cylinder, selectively. a power driven pump connected to deliver fluid to one of said valves for delivery into either end of the associated cylinder, connections between said valves to direct fluid from the other end oi the last mentioned cylinder to the other of said valves for delivery into either end of the other 01' said cylinders, a discharge port in said other valve for discharging fluid from the opposite end of said other cylinder, a control lever for each valve and a dlflerential connection between said associated control lever, valve member, and piston whereby said valve member is shifted by said control lever to initiate a movement of said piston in either direction, said piston movement being transmitted through said differential connection to return said valve member to neutral position to stop said piston, the combination of a third power cylinder disposed remotely from said pair of cylinders and means for converting said hydraulic mechanism for controlling said third cylinder comprising means for connecting the latter to the one of said control valves in place oi the cylinder associated therewith, comprising means for coupling said rockshafts together and means for releasing pressure from both ends of the replaced cylinder, whereby an adjustment of both of said control levers together eil'ects movement of each of said pistons, the valve members being simultaneously returned to neutral position by movement of the other of said pair of pistons, thereby determining the adjusted position of the piston in said remote cylinder.

16. Tractor power lift mechanism comprising, in combination, a main vertically disposed housing serving as a reservoir, a pair of coaxially aligned rockshafts journaled in the upper portion of said housing and projecting laterally from opposite ends thereof, respectively, one side wall of said housing having a plurality of laterally spaced openings therein, a pair of actuating arms fixed to said rockshafts, respectively, and extending radially therefrom through certain of said openings, hydraulic cylinders mounted on said side of the housing in vertical positions and having piston rods connected with said actuating arms, respectively, a control valve for each cylinder, duct means formed integrally with said side wall connecting one of said valves with both ends oi one of said cylinders and the other of said valves with the other of said cylinders, each valve having a member shii'table in opposite directions from a neutral position for directing hydraulic fluid into either end of the cylinder, selectively, a power driven pump connected to deliver fluid to one of said valves for delivery into either end of the associated cylinder, connections between said valves to direct fluid from the other end of the last mentioned cylinder to the other of said valves for delivery into either end of the other of said cylinders, a discharge port in said other valve for discharging fluid from the opposite end of said other cylinder, a control lever for each valve and a differential connection between said associated control lever, valve member, and piston whereby said valve member is shifted by said control lever to initiate a movement of said piston in either direction, said piston movement being transmitted through said difierential connection to return said valve member to neutral position to stop said piston, the combination of a third power cylinder disposed remotely from said pair of cylinders and means for converting said hydraulic mechanism for controlling said third cylinder comprising means for connecting the latter to the one of said control valves in place of the cylinder associated therewith, means for coupling said rockshafts together, and removable stoppers in said ducts leading to the cylinder associated with said valve to which said remote cylinder is connected, releasing fluid in both ends of the cylinder to the reservoir. whereby an adjustment 01 both of said control levers together effects movement of each or said pistons, the valve members being simultaneously returned to neutral position by movement of said coupled rockshaits. thereby determining the adjusted position of the piston in said remote cylinder.

17. Tractor power liit mechanism comprising, in combination, a main vertically disposed housing serving as a reservoir. a pair oi rockshaits Journaled in the upper portion or said housin and projecting laterally from opposite ends thereof, respectively, one side wall of said housing having a plurality of laterally spaced openings therein, a pair of actuating arms fixed to said rockshaits, respectively, and extending radially therefrom through certain 01 said openings. hydraulic cylinders mounted on said side oi the housing in vertical positions and having piston rods connected with said actuating arms, respectively, bydraulic control mechanism disposed alongside said cylinders and mounted on said side of the housing over certain other oi said openings for controlling said cylinders, and ducts for hydraulic 20 fluid, formed integrally with said main housing. interconnecting said control mechanism and said cylinders. said ducts terminating in certain of said openings serving as ports in said wall adapted to register with ports in said cylinders and control mechanism, respectively.

FRANK T. COURT.

REFERENCES CITED The iollowing reierences are of record in the iile of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,450,270.

September 28, 1948.

FRANK T. COURT It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 12, line 54, claim 1, after on and before "walP insert the word said; column 15, line 25, claim 9, for check velve read check valve 5 column 16, line 58, claim 13, strike out double acting hydraulic power cylinders, pistons; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of December, A. D. 1948.

THOMAS F. MURPHY,

able stoppers in said ducts leading to the cylinder associated with said valve to which said remote cylinder is connected, releasing fluid in both ends of the cylinder to the reservoir. whereby an adjustment 01 both of said control levers together effects movement of each or said pistons, the valve members being simultaneously returned to neutral position by movement of said coupled rockshaits. thereby determining the adjusted position of the piston in said remote cylinder.

17. Tractor power liit mechanism comprising, in combination, a main vertically disposed housing serving as a reservoir. a pair oi rockshaits Journaled in the upper portion or said housin and projecting laterally from opposite ends thereof, respectively, one side wall of said housing having a plurality of laterally spaced openings therein, a pair of actuating arms fixed to said rockshaits, respectively, and extending radially therefrom through certain 01 said openings. hydraulic cylinders mounted on said side oi the housing in vertical positions and having piston rods connected with said actuating arms, respectively, bydraulic control mechanism disposed alongside said cylinders and mounted on said side of the housing over certain other oi said openings for controlling said cylinders, and ducts for hydraulic 20 fluid, formed integrally with said main housing. interconnecting said control mechanism and said cylinders. said ducts terminating in certain of said openings serving as ports in said wall adapted to register with ports in said cylinders and control mechanism, respectively.

FRANK T. COURT.

REFERENCES CITED The iollowing reierences are of record in the iile of this patent:

UNITED STATES PATENTS Certificate of Correction Patent No. 2,450,270.

September 28, 1948.

FRANK T. COURT It is hereby certified that errors appear in the printed specification of the above numbered patent requiring correction as follows:

Column 12, line 54, claim 1, after on and before "walP insert the word said; column 15, line 25, claim 9, for check velve read check valve 5 column 16, line 58, claim 13, strike out double acting hydraulic power cylinders, pistons; and that the said Letters Patent should be read with these corrections therein that the same may conform to the record of the case in the Patent Office.

Signed and sealed this 28th day of December, A. D. 1948.

THOMAS F. MURPHY, 

